Potential integrals for uniform and linear source distributions on polygonal and polyhedral domains

Formulas for the potentials due to uniform and Linearly varying source distributions defined on simply shaped domains are systematically developed and presented. Domains considered are infinite planar strips, infinite cylinders of polygonal cross sections, planar surfaces with polygonal boundaries, and volumetric regions with polyhedral boundaries. The expressions obtained are compact in form and their application in the numerical solution of electromagnetics problems by the method of moments is illustrated.     

Experimental study of a microstrip array on high permittivity substrate

The results of an experimental study of microstrip patch antennas on moderately thick (0.02-0.03lambda_{0}) substrates with relative permittivities of 10 and 13 are reported. Measured input impedances are qualitatively similar to those of antennas on thinner substrates with lowerepsilon_{r}, but significant differences in resonant resistance are observed for probe-fed and microstripline-fed antennas. Radiation patterns of individual elements exhibit deep scallops that appear to be caused by surface wave diffraction at the edges of the substrate, but four-element monopulse patterns exhibit a usable main beam and tracking null.     

An efficient computation scheme for the free space Green's function of a two-dimensional semiinfinite phased array

A simple scheme is developed to compute the Green's function of a periodic semiinfinite array in free space. It is based on the spectral representation of the fields radiated by an infinite linear array of dipoles. Results related to successive linear arrays are added in the space domain. This summation can be accelerated tremendously by using an elementary extrapolation technique. The resulting formulation converges everywhere in the plane containing the array, and the number of terms required to achieve a given precision increases slowly away from this plane.     

K-pulse techniques for short-pulse radiation from dipole arrays

An investigation of K-pulse techniques to transmit short-time duration pulses from dipole arrays is presented. The array is analyzed from a radiation standpoint using the singularity expansion method. The analysis also makes use of the method of moments to express the array's radiation in terms of the terminal voltages and pole singularities. Following a numerical search in the complex frequency plane (from which the dominant singularities of the array are located), the time-domain waveform of the approximated K-pulse voltage is constructed. Calculated plots of the far-zone radiated electric field resulting from applying these voltages at the array terminals are presented, and their energy concentrations are compared to those of the optimum solutions     

Analysis of an infinite array of rectangular microstrip patches with idealized probe feeds

A solution is presented for the problem of an infinite array of microstrip patches fed with short current elements. The input reflection coefficient is calculated versus scan angle in an arbitrary scan plane, and the effects of substrate parameters and grid spacings are considered. The scan blindness phenomenom is observed and discussed in terms of a forced surface wave response. Measurements from waveguide simulators confirm the theory for thin substrates.     

Optimization of the transient radiation from a dipole array

The optimum solution for the transient radiation from a dipole array is derived in terms of the time-domain voltages which are required at the input terminals of dipoles in an array so that the amplitude of the transient radiated field at a specified timet_{0}and far-field positionr_{0},theta_{0}, phi_{0}is maximized. Constraints are placed on the energy and bandwidth of the input signal voltages with current restricted by Pocklington's equation. Further constraints on the sidelobe level are used to obtain a modified solution for suppressed sidelobes in the radiation pattern. Results of numerical optimization are presented, and the effects of scan angle, element spacing, and a sidelobe constraint on the optimization are discussed.     

Transient response of a receiving dipole array: bounds andmaximization

The optimum solution for a receiving array of dipole antennas connected to a load through a feed network is obtained. It is given in terms of the incident electric field waveform that maximizes, at a specific time t₀, the received voltage across a specified load impedance. This result is used to set an upper limit on the peak voltage that the antenna can deliver to a load, thus providing guidelines for the design of pulse-protection circuits. The analysis uses the method of moments to approximate the currents induced in the wires by the incident field and S-parameter techniques to describe the feed incident electromagnetic plane waves. The Lagrange multiplier technique is then used to maximize the receive load voltage. The solutions presented are based on an idealized model for the feed network; however, the analysis can be extended easily to account for loss and asymmetry of physically realizable feed networks     

Endfire tapered slot antennas on dielectric substrates

Endfire tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. We report on an investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered (LTSA) and constant width (CWSA). For antennas of all types, a good general agreement is obtained for curves of beamwidth versus length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker. An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.     

Die Erzeugung einer Sternpunktserdspannung in Netzen,ein vielseitiges Betriebsmittel der Hochspannungstechnik

Zusammenfassung Das gestreifte Zahlenspiel 3·3+1=10 scheint gerade auf die Elektrotechnik und auf die 10 Spannungen der beschriebenen Drehstrom-Hochspannungsnetze zugeschnitten zu sein. Die zehnte Spannung U_MpE liefert uns nach bisheriger übung und Erkenntniseine Isolationsprüfung, eine völlige Ablöschung und Abschaltung einfacher Erdschlüsse, eine Abstimmung von Erdschlu\spulen, einen erdschlu\mä\igen Verbundbetrieb und eine übertragung von Meldungen ohne zusätzliche Steuerleitungen.     

The optimum transient radiation from an arbitrary antenna

Bounds on the optimum transient radiation from an arbitrary antenna enclosed by a spherical surface of specified size are presented. The optimization criterion is either maximization of the radiated electric field amplitude at a specified time and far-zone position, or maximization of the radiated energy density in a specified time interval for a particular far-zone position. The latter optimization results in the prolate spheroidal wave functions. In both cases, the total energy radiated by the antenna is constrained to be 1 J, and the antenna excitation is assumed to be bandlimited. The performance of the optimum arbitrary antenna is compared to that of optimized practical antennas, such as dipoles and arrays of dipoles. The effect of a sidelobe constraint is also studied.